Psychotropic drugs intake in people aging with intellectual disability: Prevalence and predictors

Abstract Background Psychotropic medication is frequently administered to people with intellectual disability with mental health and/or behavioural problems, instead of other non‐pharmacological interventions. This study describes the mental health and behavioural problems of people aging with intellectual disability, their psychotropic medication intake, and the factors contributing to a greater medication intake. Method The sample consisted of 991 people with intellectual disability over 45 years. Descriptive statistics and multinominal logistic regression were carried out. Results Antipsychotics were the most used psychotropic drug. Older people with mild intellectual disability living in institutions and affected by mental health and behavioural problems were more likely to take larger amounts of psychotropic medication. Conclusions Antipsychotics continue to be widely used by people with intellectual disability and mental and behavioural health problems, especially those in institutionalised settings. Future research should consider if medication intake could be reduced providing better supports in the community and non‐pharmacological interventions.


| INTRODUCTION
Psychotropic medication is frequently used to treat people with intellectual disability who exhibit mental health and behavioural problems instead of considering other nonpharmacological interventions such as behavioural therapy and positive behavioural support (Tan et al., 2015). This results in the use of high doses of medication (Bowring et al., 2017), especially antipsychotic drugs (Tsiouris, 2010), that are not always necessary. In fact, the proportion of people with intellectual disability who are prescribed psychiatric drugs is larger than that of people with intellectual disability who have a diagnosis of mental illness (Aguilar, 2019;Sheehan et al., 2015;Tsiouris et al., 2013).
The research carried out by Folch et al. (2019) reports that people with intellectual disability take psychotropic drugs even when many of them do not have a clinical diagnosis of mental illness. The study by Sheehan et al. (2015) reflects a similar result: 71% of the people with intellectual disability who use antipsychotics have no record of mental illness in their history. This leads us to consider their use as a mean of 'restraining' any problematic behaviour that may occur, which is consistent with previous literature (Bowring et al., 2017;de Kuijper et al., 2010;Deb et al., 2015;Gothelf et al., 2008;Sheehan et al., 2015).
In this regard, there is evidence that the presence of behavioural problems is associated with the start and maintenance of psychotropic drug therapy (Song et al., 2020), which is often chosen over other less invasive alternatives (i.e., psychological therapy; Deb et al., 2009;Valdovinos et al., 2017). Pharmacological interventions are commonly used to manage behavioural problems in spite of its numerous side effects (Sheehan, 2018) and the lack of awareness about the safety of psychotropic medications in population with intellectual disability (G omez, Navas, Verdugo, & Tassé, 2021). These adverse effects may hinder the diagnosis of other health problems in the population with intellectual disability .
Besides behavioural problems, there are several factors that, according to the scientific literature, contribute to a greater intake of psychotropic drugs among people with intellectual disability. Living environment as a factor that may explain a greater or lesser use of psychiatric medication has also been the object of study, although results are still contradictory. While certain authors report that the use of psychotropic medication is greater among people with intellectual disability who live in community settings (Spreat et al., 2004), others claim that segregated contexts are associated with a greater use of psychiatric medication (Lunsky & Modi, 2018;O'Dwyer et al., 2016).
Increased levels of psychotropic medication prescription have also been observed in individuals with intellectual and developmental disabilities who require more extensive supports (Axmon, El Mrayyan, et al., 2019), since they may present more mental health issues requiring psychopharmacological treatment . Nevertheless, it is important to bear in mind that behavioural problems are attempts at communication by individuals who may lack the capacity to express themselves otherwise  and that their assessment in people with more severe disabilities might be difficult due to their communication difficulties (Tassé et al., 2017). This could lead professionals to mistakenly consider these behavioural manifestations to be symptoms of a mental health disorder rather than responses to contextual changes or specific social situations.
Older age also appears to be positively associated with the intake of psychotropic medication Bowring et al., 2017). In aging people with intellectual disability, polypharmacy and its associated risks to their health are far greater (Axmon et al., 2017;El Mrayyan et al., 2019;O'Dwyer et al., 2018), so the need to prescribe psychotropic drugs should be carefully assessed (O'Dwyer et al., 2018).
Adulthood and old age are stages of the life cycle that involve major changes and transitions. Already 20 years ago, the World Health Organization warned about the need to improve our knowledge and sensitivity as regards stressors that are associated with the general process of aging and could negatively affect the emotional wellbeing of people with intellectual disability (Hogg et al., 2000). Even though we are currently aware of the impact of transitions such as retirement (Amado et al., 2013) or stressors such as the grieving process (Dodd et al., 2005) on aging people with intellectual disability, the behavioural expressions that are triggered by them still drive professionals to overprescribe psychotropic medication (Axmon et al., 2017;Eady et al., 2015). Research on the prescription of psychotropic medication among this population group is, however, limited (Chitty et al., 2016;O'Dwyer et al., 2017), and stronger scientific evidence concerning the use and treatment with psychotropic drugs in aging people with intellectual disability is required (Sheehan et al., 2015).
For the reasons mentioned above, the aims of this study focus on: (a) describing the mental health and behavioural problems presented by aging people with intellectual disability, as well as the type of psychotropic medication they use; and (b) analysing the factors that predict a greater intake of psychiatric drugs in older people with intellectual disability.

| Participants
The sample consisted of 991 adults with administratively defined intellectual disability (i.e., receiving services aimed at population with intellectual disability) aged between 45 and 88 (M = 55.3; SD = 7.3). Table 1 gathers the sociodemographic data of the study participants.
A total of 353 informants participated in the study by completing a survey, which will be subsequently detailed, on the health status of the person with intellectual disability. Most of them were females (75.4%) and the average age was 50.2 years old (SD = 15.8). More than half were professionals (58.9%) and almost 40% were family members. All of them had known the person assessed for at least 12 months. Most of them (74.0%) had daily contact with the person with intellectual disability.

| Instrument
An ad hoc questionnaire was prepared to obtain information about the health status of aging people with intellectual disability. Its details T A B L E 1 Sociodemographic data of people with intellectual disabilities participating in the study

| Procedure
Initial contact was established with 1068 organisations that are part of the four main service providers for people with intellectual disability in Spain (Plena inclusi on, Down España, ASPACE España, Autismo España), out of which 227 (21.0%) expressed an interest in taking part in the study given that there were aging individuals among their users.
The final sample was obtained from 83 of these organisations, located in 34 of the 50 Spanish provinces.
The survey used in this cross-sectional study was sent by post or email (according to preference) to the participating organisations, together with the following two documents: (a) an informed consent form that was to be returned by the professionals or relatives before recording the data, and (b) an information letter stating the study objectives, method, funding sources and other relevant information regarding the research, as well as a contact address for further information if required. The research team maintained continuous contact with the respondents both by email and telephone to solve any questions that might arise throughout the data collection process.
Once all the surveys were received (by postal mail or e-mail), the data were transferred to an SPSS 25 database for subsequent analysis. Informants were contacted by phone or email to request clarification of the information provided when necessary.
Regarding medication, informants provided data on the name of psychotropic drugs taken by the person, but in many cases did not specify the dosage. The research team decided to limit the analysis to the type of drug, and the first author coded this information taking into account its main use. The answers were classified by the first author into: anxiolytics, antidepressants (including mood stabilisers or euthymizers) and antipsychotics, so results could be compared with those of previous research (e.g., Lunsky & Modi, 2018;Tsiouris et al., 2013), taking also into account that these are the psychotropic drugs most widely used in the general population with intellectual disabilities (e.g., Bowring et al., 2017;Sheehan et al., 2015;Song et al., 2020).
This procedure was approved by the Bioethics Committee of the University of Salamanca. All procedures performed in this research were in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

| Data analysis
Descriptive statistics (frequencies and percentages) were calculated to summarise the prevalence of medication use. The association between medication use and the presence of behavioural or mental problems). Information on these variables was collected through the survey previously described (sections a and b). All the variables were entered simultaneously into the model. No special treatment of missing data on the different variables was performed, since they did not account for more than 3% of the total in any case. No outliers that might significantly affect the data analysis were detected.
Multicollinearity among the independent variables was tested using the variance inflation factor (VIF) with a cutoff value of <2 (John, 1983), so that a variable's VIF value being above 2 would indicate collinearity associated with such variable. All the VIF values were below 2, so multicollinearity among variables was ruled out.
The data were analysed using IBM SPSS Statistics version 25 software. The researchers set the significance level at α = .05.

| Use of psychotropic medication
Of the entire sample, 38.4% (n = 381) used some type of psychotropic medication. Antipsychotics were the most common (n = 274; 71.9%), followed by antidepressants (n = 187; 49.1%) and anxiolytics (n = 181; 47.5%). Table 3 shows the distribution of psychotropic medication in people with mental health or behavioural problems, both types of problem, and none.

| Factors that predict greater psychotropic medication use in older people with intellectual disability
The data yielded by the multinominal logistic regression are shown in Tables 5 and 6. Table 5 shows the results for people taking one psychotropic drug and Table 6 shows the results for people taking two or more psychotropic drugs. The results of Table 6 suggest that being older, having mild intellectual disability, living in a residential setting, having mental health conditions, and exhibiting behavioural problems contribute to increasing the probabilities of using two or more psychotropic drugs. The effect of the sex and type of communication variables on the levels of the dependent variable was not significant. Moreover, as regards polypharmacy, the results of Table 6 show how as age increases by one unit, so does the probability of using two or more drugs at a rate of 1.04 (1/.964). Having mild intellectual disability also proved a significant predictor of polypharmacy: individuals with mild intellectual disability were twice as likely to use two or more psychotropic drugs as people with severe intellectual disability (b = .689; Wald χ 2 (1991) = 6.37; p = .012; OR = 1.99; CI (95%): 1.17-3.40). The probability of taking two or more psychiatric drugs was 2.76 times higher when the individual lived in a residential facility as compared to living in a community setting (b = 1.02; Wald χ 2 (1991) = 24.58; p < .001). Regarding people who had some type of mental health issue, the probability of using two or more drugs proved

| DISCUSSION
The first objective of this study was to describe the mental health and behavioural problems exhibited by people with intellectual disability over the age of 45 in Spain, as well as the type of psychotropic medication they use. Destructive disorders, anxiety disorders, depressive disorders and schizophrenia spectrum disorders were the most prevalent mental health conditions in this population group. The most frequently reported behavioural problems were stereotyped behaviour, aggressive behaviour, and disruptive behaviour. Regarding psychotropic drugs, 38.4% of the sample used any psychotropic drug. This result is in line with the data described by Bowring et al. (2017), and Holden and Gitlesen (2004), who respectively reported that 37.7% and 37.4% of their samples used psychotropics.
Antipsychotics were the most frequently used psychotropic medication, which is consistent with the results of previous studies both in adults with intellectual disability (Bowring et al., 2017;Lunsky & Modi, 2018;Perry et al., 2018;Song et al., 2020) and in older adults with intellectual disability (O'Dwyer et al., 2017). The intake of anxiolytics, antidepressants and antipsychotics was greater among individuals with destructive disorders, stereotyped behaviour, disruptive behaviour, and aggressive behaviour.
This result is consistent with previous studies where psychiatric medication is higher in individuals who exhibit more severe challenging behaviours (Deb et al., 2015). The reason for this greater use could be that public health professionals are not adequately trained to properly address the behavioural issues of people with intellectual disability and may use psychotropic medication instead of other strategies (e.g., positive behavioural support), since they lack the necessary understanding of chemical restraint, its side effects, and alternatives (Donley et al., 2012). Another possibility is that certain behavioural problems could be misinterpreted as psychiatric disorders rather than as responses of the person with intellectual disability to certain envi-  The second aim of the study was to analyse the extent to which certain variables predict the intake of psychotropic medication in older people with intellectual disability. Older age, mild intellectual disability, residential settings, and having mental health and behavioural problems contribute to a greater intake of psychotropic medication among aging people with intellectual disability. Specifically, our findings suggest that as the participants' age increases, so does the probability of using more psychotropic medication, as already noted by Bowring et al. (2017). This increase could be due to difficulty in identifying the onset of age-associated diseases such as dementia, whose prevalence in older adults with intellectual disability is higher than in older adults without intellectual disability (Cooper et al., 2018).
Likewise, emotional stress associated with the transitions at this stage of life could be triggering behavioural disorders that are addressed through psychopharmacological therapy (Deutsch & Burket, 2021;Kelly & Su, 2015).
As for the severity of intellectual disability, the participants with mild intellectual disability showed twice as many probabilities of using more than one psychotropic medication than people whose intellectual disability was more severe, although there are authors who claim that the severity of intellectual disability does not predict the use of psychotropic medication (Bratek et al., 2017;Holden & Gitlesen, 2004;Tsiouris et al., 2013).
Regarding living environment, our results suggest that living in residential settings is associated with a greater intake of psychotropic drugs, which is consistent with the findings of other studies both on adults (Kelly & Su, 2015;Lunsky & Modi, 2018) and on individuals who are aging (Bratek et al., 2017;O'Dwyer et al., 2017). This result may be due in part to the characteristics of residential environments (e.g., overcrowding may increase the occurrence of challenging behaviours by some users; McGillivray & McCabe, 2005). On the other hand, direct support professionals in these settings assist a large number of people, and when problematic behaviours appear, they might use restrictive practices (Saloviita, 2002) such as chemical restraint, as opposed to more individualised ones such as positive behavioural support.
In this study, the probability of using two or more drugs was Finally, behavioural problems also seemed relevant in psychotropic medication intake among aging individuals with intellectual disability. According to our results, the probability of polypharmacy was almost three times greater when the assessed individuals exhibited T A B L E 6 Results of the multinomial logistic regression model for people taking two or more psychotropic drugs some type of behavioural issue. This is in line with other findings where behavioural problems were associated with starting psychotropic medication, in general (Song et al., 2020) and antipsychotics, in particular (de Kuijper et al., 2010). It would be interesting for future lines of research to investigate whether behavioural problems also predict the intake of one psychotropic drug and not only two or more as concluded in our study. This will shed more light on the relationship between behavioural problems and psychotropic drugs intake.
Because of the negative impact that the side effects of psychotropic medication have on the person's quality of life, it is not the most advisable treatment to address behavioural problems (Scheifes, Walraven, et al., 2016). Moreover, medication side effects themselves may contribute to the development of challenging behaviours, making it necessary to reduce doses, discontinue the drug, or eliminate polypharmacy (Deutsch & Burket, 2021). Psychotropic medication should be reduced, as suggested in the NICE Guidelines (2015) guidelines, to challenging behaviours that do not respond to alternative interventions or that might involve a serious threat to the person or others.
This study is, to date, the only one in Spain to provide a detailed analysis of the use of medication in people with intellectual disability over the age of 45. The sample size allows for estimates with high statistical power. Nonetheless, this work has certain limitations that should be considered. First, the sample used was selected among people who attended third-sector organisations, which makes it a convenience sample. According to some authors, the psychotropic prevalence estimates in studies where this type of clinical samples is used tend to be quite high (Bowring et al., 2017). Second, this study does not include older population without intellectual disability among its participants, which precludes an analysis of the extent to which both the prevalence of mental health and behavioural problems and psychotropic drug consumption differ between these two groups. Third, the doses of psychotropic medication were not recorded in all cases due to missing information. It would be interesting to take this into account in future studies to determine how to achieve the desired effect with the lowest possible dose when medication is needed, thus minimising the onset of adverse effects associated with these psychotropic drugs. Finally, and although the research team was available to resolve any doubts or setbacks that could arise during the data collection process, given the exploratory nature of the study we relied on proxy reports due to the difficulties associated with reviewing medical/behavioural records for all participants. Also, coding of the psychotropic drugs consumed by the participants was carried out by a single researcher, so no data on inter-rater reliability can be provided. Future research studies should aim to overcome this limitation by reviewing the medical/psychiatric history of the participants, applying on-site standardised behavioural assessment instruments, and creating a medication record sheet that can be filled out by the person's referring physician, indicating dosage.
Future research lines should also elaborate on how to address behavioural problems in aging people with intellectual disability using nonpharmacological intervention alternatives (e.g., positive behavioural support, active support) to determine their effectiveness and prioritise their choice in cases of challenging behaviours that respond adequately to this type of interventions.

| CONCLUSION
This study analysed the pattern of psychotropic drug intake in 991 aging individuals with intellectual disability. The results obtained suggest that the greatest use of anxiolytics, antidepressants and antipsychotics was made by individuals with destructive disorders, stereotyped behaviour, oppositional and/or aggressive behaviour. Older age, mild intellectual disability, living in residential facilities, mental health conditions and behavioural problems contribute to increase the amount of psychotropic medication among aging people with intellectual disability.